JavaScriptGenerator generates blocks of JavaScript code that allow you to
change the content and presentation of multiple DOM elements. Use this in
your Ajax response bodies, either in a <script> tag or as plain
JavaScript sent with a Content-type of "text/javascript".

Create new instances with PrototypeHelper#update_page or with
ActionController::Base#render, then call
#insert_html, #replace_html, #remove, #show, #hide, #visual_effect, or any
other of the built-in methods on the yielded generator in any order you
like to modify the content and appearance of the current page.